Total-transfer comprehensive three-dimensional gas chromatography with time-of-flight mass spectrometry

Although comprehensive two-dimensional (2D) gas chromatography (GC x GC) is a powerful technique for complex samples, component overlap remains likely. An intriguing route to address this challenge is to utilize the additional peak capacity and chemical selectivity provided by comprehensive threedimensional (3D) gas chromatography (GC(3)), especially with time-of-flight mass spectrometry detection (GC(3)-TOFMS). However, the GC(3)-TOFMS instrumentation reported to date has employed one or both modulators with a duty cycle < 100%, making the potential gain in detection sensitivity over GC x GC modest, or perhaps even worse. Herein, we describe instrumentation for GC(3)-TOFMS in which both modulators provide total-transfer (100% duty cycle). Specifically, the instrument is based on the facile modification of a commercial thermally modulated comprehensive GC x GC-TOFMS platform for modulation from the D-1 column to the D-2 column, with recently described dynamic pressure gradient modulation (DPGM) as the second modulator from the D-2 column to the D-3 column, which is a total-transfer flow modulation technique. Area measurements of D-1 peaks are compared to the sum of D-3 peak areas to validate the assumption that total-transfer from D-1 to D-3 is accomplished. Additionally, peak heights were amplified by as high as a factor of 177 (x = 130, s = 47) via comparison of D-1 peak heights to the maximum D-3 peak heights. Column selection is explored, with emphasis on the resulting peak width-at-base on each dimension and usage of D-3 space as evaluation metrics. Using a nonpolar x polar x ionic liquid column combination, an effective peak capacity which considers modulation-induced broadening as high as 32,300 for select analytes was achieved (<(x)over bar> = 19,900, s = 10,700). The analytical benefits of employing three selective phases, mass spectrometry detection, and total-transfer modulation are explored with separations of a metabolomics-type sample, i.e., derivatized porcine serum, and a jet fuel spiked with various sulfur-containing compounds. (C) 2020 Elsevier B.V. All rights reserved.